Fluid control system

ABSTRACT

A fluid control system for an elevating scraper incorporating a master control valve for selectively directing fluid to a floor gate cylinder and an ejector gate cylinder, and a pilot sequence valve for sequentially operating said master control valve to assure that fluid will be initially directed to the floor gate cylinder and then subsequently to the ejector gate cylinder; there being a fluid line connecting the floor gate cylinder and the pilot sequence valve for passage of fluid to the latter after the floor gate has been fully extended.

v United States Patent 1191 1111 3,815,472 Schantz 1 June 11, 1974 1 1 FLUID CONTROL SYSTEM 2,301,028 11/1942 Esch 91/412 x 75 Inventor: Ronald K. Schantz, Morton, 111. 2, 51,515, 731 Assigneez Westinghouse Air Brake Company, 3,183,840 5/1965 Conover Pittsburgh, Pa. 3,207,182 9/1965 Edmunds 251/297 X [22] Filed: 15, 1973 Primary Examiner-Edgar W. Geoghegan [21 1 Appl. No.: 332,947 Atwrney, Agent, or FirmRobert J. Eck

I Related US. Application Data ABSTRACT I [62] D1v1s1on of Ser. No. 174,595, Aug. 25, 1971, Pat. No.

3,733,964. A fluid control system for an elevating scraper mcorporating a master control valve for selectively direct- 52 us. (:1 91/189, 91/281, 91/411 R, g fluid to a floor gate cylinder and an ejector gate 60/97 SE cylinder, and a pilot sequence valve for sequentially [51] Int. Cl. F011 15/00 p ng i m r on r l lve o assure that fluid 58 Field of Search 60/97 SE, 420; 91/412, will be initially directed to the floor gate cylinder and 91 29 3 9 1 9 193; 251 297 then subsequently to the ejector gate cylinder; there being a fluid line connecting the floor gate cylinder [56] References Cit d and the pilot sequence valve for passage of fluid to the UNITED STATES PATENTS latter after the floor gate has been fully extended. 2,298,457 10/1942 Berges 91/318 1 Claim, 5 Drawing Figures PATENTEDJUM 1 1 m4 SHEET 1 OF 4 PATENTEDJUM 1 1 0914 saw nor 4 FLUID CONTROL SYSTEM This is a division of application Ser. No. 174,595 filed Aug. 25, 1971, now US. Pat. No. 3,733,964, granted May 22, 1973.

BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates in general to an elevating scraper, and more particularly, to a fluid control system therefor.

Heretofore it has been a practice in the elevating scraper art to provide simultaneous introduction of fluid pressure to both the floor gate and the ejector gate cylinders, relying on the resistance of the load to create a sequential movement of said floor and ejector gates, such as shown and described in US. Letters Patent issued to J. E. Hancock US. Pat. No. 3,066,429. Such simultaneous actuation of both the floor gate and ejector gate cylinders was unacceptable to the industry because it developed inconsistent and variable results. Oftentimes a floor gate would freeze or bind thereby resulting in considerable pressure exerted by the ejector gate, causing great compaction and conducing to a more difficult unloading. Moreover, the ejector gate would frequently force material through the elevator or through the top of the earth collecting bowl, thereby causingdamage to the elevator as well as causing undesired spillage of the load.

By 'the present invention, the above disadvantages have been alleviated as the floor gate cylinder and the ejector gate cylinder are truly sequential in operation; the ejector gate" cylinder being precluded from movement until the floor gate cylinder has been fully extended. By so doing a substantial portion of the material in the bowl will be released through the floor opening prior to the movement of the ejector gate cylinder thereby requiring less initial pressure and enhancing the life of the ejector gate cylinder. In view of the sequential operation of the floor gate and ejector gate cylinders, there is no compaction problems as above described nor is there any opportunity for the material in the bowl to be forced outwardly through the elevator or through the top of the bowl.

BRIEF DESCRIPTION OF THE DRAWINGS -FIG. 1 is a side elevational view in partial section of an elevating scraper having a flow control system constructed in accordance with and embodying the present invention.

FIG. 2 is a schematic hydraulic diagram illustrating the pilot sequence valve and the flow control system in a position for extending the floor gate.

FIG. 3 is a schematic hydraulic diagram illustrating the pilot sequence valve and the flow control system in a position for effecting extension of the ejector gate.

FIG. 4 is a schematic hydraulic diagram illustrating the pilot sequence valve and the flow control system in a position for effecting simultaneous retraction of the floor gate and the ejector gate.

FIG. 5 is a vertical transverse section taken on the line 5-5 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings whereinlike reference characters designate like corresponding parts, there is shown in FIG. 1 an elevating scraper 20, or other similar earth moving vehicle, comprising a mobile tractor 21 having a frame 22 to which is connected a yoke 23 extending rearwardly for connection to the frame 24 of an earth collecting bowl 25. The tractor 21 is provided with the customary power or drive connection to the earth collecting bowl 25; and is also provided with a hydraulic ram cylinder 26 connecting the frame 22 of the tractor 21 with the frame 24 of the earth collecting bowl 25 for adjusting the height of the latter above ground. Suitably mounted to the forward end portion of the frame 24 is an elevator 27, such as of the customary chain and paddle type, which operates in a wellknown manner to scrape earth into the bowl 25. The rearward end of frame 24 is supported above ground by an axle 28 having its end portions connected to wheels 29.

Said earth collecting bowl 25 comprises a pair of spaced-apart side walls 30, 30' which are integral at their lower edge portion with a floor or bottom wall 31; said bottom wall 31 having a forward edge 31' terminating spacedly rearwardly from the forward end portion of side walls 30, 30' for developing an opening 32 within the earth collecting bowl 25. Presented in normally closing relationship with said opening 32 is a floor gate 33 having its rearward edge 34 located spacedly rearwardly of the forward edge 31 of bottom wall 31, when the floor gate 33 is in fully retracted position as illustrated in FIG. 1. Formed integral with the forward edge 35 of the floor gate 33 is a lug 36 which is suitably connected to the outer end portion of a piston 37 of a fluid responsive cylinder 38, of the doubleacting type, which is securedto the frame 24.

Provided intermediate the side walls 30, 30' transversely within said earth collecting bowl 25, there is provided an ejector gate 39 having a width slightly less than the width between side walls 30, 30' and a height greater than same. The lower end edge-40"of said ejector gate 39-is in engagement with a slide plate 41 being forwardly and downwardly inclined and located upwardly of the bottom wall 31. The forward portion of said slide plate 41 is formed integral with a depending skirt 42 which engages the forward edge 31' of the bottom wall 31. Mounted on the rearward face of said ejector gate 39 there is a thrust frame 43 attached to the outer end of a piston 44 of a fluid responsive cylinder 45, of the double-acting type, which is mounted to the frame 24. As will be seen, the fluid responsive cylinders 38 and 45 operate to extend and retract the associated pistons 37 and 44, respectively, for moving the floor gate 33 and the ejector gate 39, respectively.

Referring to FIG. 2, said fluid responsive cylinder 38 is formed with forward and rearward end walls 46, 46' and an intervening side wall 47, said walls cooperating to define a compartment 48. Received within compartment 48 is a piston head 49 which is connected to the floor gate remote end portion of said piston 37, which latter projects outwardly endwise through said rearward end wall 46'. Immediately adjacent said rearward end wall 46', the side wall 47 is provided with a port 50 which is connected by a branch line 51 and a conduit 52 to a master control valve M, which will be described in detail hereinbelow. The forward end wall 46 of the fluid responsive cylinder 38 is furnished with a port 53 which is connected by conduit 54 to the master control valve M. Provided within the side wall 47, spacedly downwardly from rearward end wall 46', there is a port 55 which is connected by conduit 56 to a pilot sequence valve V, which will be described in detail hereinbelow. It will be observed that said port 55 is spaced downwardly from the rearward end wall 46 a distance slightly greater than that of the thickness dimension of the piston head 49 when the latter is in engagement with the rear end wall 46 (FIG. 3).

Said fluid responsive cylinder 45 comprises forward and rearward end walls 56, 56' and an intervening side wall 57; said walls cooperating to define a compartment 58 for slidably receiving a piston head 59 which is connected to the ejector gate remote end portion of piston 44. Furnished within the side wall 57 immediately adjacent the forward end wall 56 of said fluid responsive cylinder 45 there is a port 60 which is connected by said branch line 51 and the conduit 52 to the master control valve M. It will be observed that both ports 50 and 60 offluid responsive cylinders 38 and 45 are connected in parallel by said branch line 51 so that fluid passing through conduit 52 will be equally dispersed to the respective compartments 48 and 58. Formed within the rearward end wall 56 there is a port 61 which is connected by conduit 62 to the master control valve M, as will be described.

MASTER CONTROL VALVE M Referring now to FIGS. 2-4 of the drawings, the master control valve M comprises a pair of spaced-apart spool valves 100, 100 which are identical in every feature so that spool valve 100 need only be described; it being understood that like elements of the spool valve 100 which correspond to the elements of the spool valve 100 will be given like numerals to facilitate understanding and to avoid unnecessary repetitive explanation.

Spool valve 100 comprises a body 101 having a top wall 102, a bottom wall 103 and an intervening side wall 104. Extending longitudinally through said body 101 there is a bore 105 within which is received a spool 106 having opposed upper and lower end portions 107, 108 and a central valve portion 109, the latter being connected to the upper and lower end portions 107, 108 by rods 110 and 111, respectively. The upper and lower end portions 107, 108 are adapted to be moved axially inwardly and outwardly of upper and lower fluid housings 112, 113, respectively, which are conveniently mounted on the top and bottom walls 102, 103, respectively. Each fluid housing 112 and 113 is provided with a conventional resilient mechanism (not shown) for urging the spool 106 into a predetermined, neutral position, which will be described.

The rods 110, 111 are of a reduced diameter for cooperating with the wall of bore 105 and the spool 106 to define upper and lower fluid passages 114 and 115, respectively. The central valve portion. 109 is provided with a groove 116, of relatively narrow extent, which is adapted to be presented in registering relationship with a passage 117 located in body 101, said passage 117 being connected by a line 118 to the adjacent valve body 101' of the spool 100'. Said groove 116 is in communication (not shown) with a longitudinally disposed, relatively enlarged recess 119 on the opposed side portion of the central valve portion 109, which recess 119 is adapted to effect selective communication between ports 120, 1 21, and 122 furnished within the body 101. Said port 120 is connected by said conduit 52 to the branch line 51 for communicating spool valve 100 with the ports 50 and 60 of the fluid responsive cylinders 38 and 45, respectively; the port l21 by conduit 123 to the discharge side of a pump 124, the intake side of which is connected by a line 125 to a reservoir 126 containing hydraulic fluid; the port 122 by said conduit 54 to the port 53 of the fluid responsive cylinder 38 for communicating the spool valve therewith.

Downwardly of the port 122, the side wall 104 of body 101 is provided with a return port 127 which is connected by return lines 128 and 129 to said reservoir 126. Said return port 127 opens into said lower fluid passage and is in axial alignment with a port 130 of a fluid by-pass 131 which is presented longitudinally within body 101 in axially parallel relationship to bore 105. The other end portion of said fluid by-pass 131 is connected to a port 132 which opens into the upper fluid passage 1 14 of bore 105. Thus, it will be observed that the fluid by-pass 131 maintains the upper and lower fluid passages 114 and 115 in communication at all times.

The spool 106 of spool valve 100 is adapted for movement into three positions; namely, a neutral position (FIG. 3), a gate extended position (FIG. 2), and a gate retracted position (FIG. 4). In the neutral position, illustrated in FIG. 3, the valve central portion 109 is positioned within bore 105 to block the ports and 122 and to establish communication between the conduit 123 and the passage 117 through the recess 119 and the groove 116 for directing fluid to said spool valve 101'.

In the gate extended position (FIG. 2), the spool 106 is lowered for blocking the passage 117 and establishing communication between ports 122, 121 through recess 119; between ports 120 and 132 through the upper fluid passage 114; and between the port and the return port 127 through the lower fluid passage 115. Therefore, fluid will be directed from reservoir 126 through the conduit 123, recess 119, conduit 54 to the port 53 for effecting extension of the piston 37; the fluid on the upward side of piston head 49 being returned through the port 50, branch line 51, conduit 52, upper fluid passage 114, by-pass 131, lower fluid passage 115, and return lines 128 and 129 to the fluid reservoir 126.

In its gate retracted position (FIG. 4), the spool 106 is moved upwardly of its neutral position for blocking the passage 117 and establishing communication between the ports 120 and 121 through recess 119; and between the port 122'and the return port 127 through the lower fluid passage 115. Therefore, fluid from the reservoir 126 will be directed through conduit 123, recess 119, conduit 52, branch line 51 to the ports 50 and 60 of fluid responsive cylinders 38, 45, respectively, for effecting simultaneous retraction of the pistons 37 and 44, respectively. The fluid on the downward side of the piston head 49 of the fluid responsive cylinder 38 is returned through port 53, conduit 54, lower fluid passage 1 15, and return lines 128 and 129 to the fluid reservoir 126.

As noted hereinabove the elements of the spool valve 100 which correspond identically to the spool valve 100 have been designated with like numbers in FIG. 2. Therefore, said spool valve 100' comprises a body 101 havingports 120'; 121', and 122' and a return port 127'; the port 120' being connected by the conduit 133 to the conduit 52; the port 121 being connected to the line 118 for establishing communication between the spool valves 100 and 100; the port 122' being connected by the conduit 62 to the port 61 of cylinder 45; and the return port 127' being connected by the return line 129 to the reservoir 126. The by-pass 131 of said valve body 101 is in communication through the ports 130' and 132' to the upper and lower fluid passages 114 and 115, respectively, each of which are defined by the wall of bore 105' and the spool 106' in the region of rods 110 and 111', respectively.

The spool 101' is also adapted to be axially moved into three positions; namely, a neutral position (FIG. 2), a gate extended position (FIG. 3), and a gate retracted position (FIG. 4). In the neutral position (FIG. 2), said spool 106' is positioned so that said central valve portion 109' blocks the ports 120' and 122 and establishes communication, through the recess 119 and the groove 116', between the line 118 and the passage 117 which latter is connected by the line 134 to the return line 129 for return flow to the reservoir 126. Thus, if both spools 106 and 106' are in neutral position (not shown), fluid from the reservoir 126 will be continuously circulated through the master control valve M and returned thereto.

In its gate extended position (FIG. 3), said spool 106 is lowered for blocking the passage 117' and establishing communication between the ports 121 and 122' through the recess 119 so that fluid passing through the line 118 will be directed through the conduit 62 to the port 61 of said fluid responsive cylinder for extending the piston 44. Communication is also established between the ports 132' and'120 through the upper fluid passage 114' and between the port 130' and the return port 127' through the lower fluid passage 115', so that flui'd on the upper side of the piston head 59 will be directed through said branch lineSl, conduits 52 and 133, by-pass 131', and return line 129 for return to the reservoir 126.

In the gate retracted position (FIG. 4) said spool 106' is raised so that said central valve portion 109' blocks the passage 117 and establishes communication between the ports 120' and 121 through recess 119' and between ports 122' and return port 127' through lower fluid passage 115. Thus, upon retraction of piston 44, fluid on the downward side of the piston head 59 will be directed through the conduit 62 and the return line 129 for return to said reservoir 126.

PILOT SEQUENCE VALVE V The upper fluid housing 112, 112 of each spool valve 100, 100' is connected by lines 135, 135, respectively, to the pilot sequence valve V comprising a body 200 having end walls 201, 201 connected by a side wall 202. Provided longitudinally through body 200 is a bore 203 defining a valve chamber 204 which is connected with lines 135, 135'; by ports 205, 205', respectively, provided in the side wall of 202. Diametrically opposed to ports 205, 205' and axially therebetween there is provided in side wall 202 a feeder port 206 connecting the valve chamber 204 through a pilot line 207 to a manual control valve C, which in turn is connected to a source of pilot fluid 208 as will be described. Each end wall 201, 201' is provided with a port 209 and 210, respectively, which are in axial alignment with the axis of the valve chamber 204. The port 210 is connected by the conduits 211 and 212 to the manual control valve C; and port 209 by said conduit 56 to said port provided in the side wall 47 of the fluid responsive cylinder 38. Additionally, provided in communication with port 209 is a return line r which interconnects the port 209 with the pilot fluid reservoir 208 for relieving the fluid pressure within the pilot sequence valve V.

Provided within valve chamber 204 there is a spool 213 comprising a forward portion 214, a rearward portion 215, and a diametrically reduced portion 216 therebetween. Located on either side of the diametrically reduced portion 216, there is a circumferential passage 217, 217 each being in communication with said return line r through an axial bore b fashioned within said spool 213 to open endwise through said forward portion 214 into the port 209.

The valve spool 213 is adapted to be moved axially between two positions within the valve chamber 204 responsive to fluid pressure entering the ports 209 and 210, and acting on the respective end faces of the forward and rearward portions 214 and 215. In one position, the diametrically reduced portion 216 establishes communication between the feeder port 206 and the port 205 for interconnecting the pilot line 207 with the line and in the other position between the feeder port 206, and the port 205 for connecting the pilot line 207 to the line 135. Accordingly, by the employment of pilot sequence valve V, the pilot fluid will be directed to the. master control valve M alternatively through lines 135 and 135', respectively, for effecting the sequential extension of the floor gate 33 and the ejector gate 39.

The rearward portion 215 of the spool valve 213 is formed with a pair of spaced-apart circumferential grooves g, g for alternatively receiving spring-loaded ball detents, collectively designated 218 (FIG. 5) for maintaining said spool valve 213 in a preselected position. Since each of the ball detents 218 are identical in construction, only one will be described; it being understood that the other ball detents 218 operate in the same manner.

Said valve body 200 is furnished in its side wall 202 with a plurality of circumferentially spaced-apart bores 219, each of which receive a ball 220 which projects into the valve chamber 204 for reception within either of said circumferential grooves g or g. Each bore 219 is formed with a tapped counterbore 223 for threadedly receiving the shank 224 of a lock screw 225; said shank 224 having an axial bore 226 therein for receiving one end portion of a helical spring 227, the other end portion bearing against the related ball 220 for urging same into the selected groove g or g. Each lock screw 225 is provided with an enlarged head 228 which is received within a recess 229 formed within a flat 230 machined in the side wall 202 of the body 200. The recess 229 cooperates with the bore 219 to define a seat against which the head 228 abuts. Accordingly, the ball detents 218 will retain spool valve 213 in a predetermined position until the fluid pressure at one of the opposed ends at ports 209 and 210 is sufficient to overcome the bias of the helical spring 227 for urging the valve spool 213 into its other position.

MANUAL CONTROL VALVE C Conveniently provided on tractor 21 is a manual control valve C comprising a body 300 having end walls 301, 301' and a side wall 302; there being a longitudinal bore 303 extending through the end wall 301', which bore 303 terminates spacedly from end wall 301. Provided for slidable reciprocal movement within the ing a handle 305 on its outer end portion for use in thev selective manipulation of the plunger 304 into a desired position. The plunger 304 incorporates a pair of spaced-apart heads 306, 307, which are of the same diameter as that of bore 303. lnterconnecting the heads 306 and 307 is a diametrically reduced portion 308 cooperating with the heads 306 and 307 and the adjacent wall of the bore 303 to define a fluid passage 309.

The side wall 302 of the body 301 is provided with ports 310, 311, 312 and 313; the ports 310 and 311 being connected to feeder port 206 and port 210, respectively, of pilot sequence valve V through said pilot line 207 and conduits 211 and 212, respectively, and

. port 312 being connected by the return line 314 to the pilot reservoir 208. The port 313 is connected by line .3 to the discharge side of a pump 316, the intake side of which is connected by a line 317 to the pilot reservoir 208. It will be observel that the port 313 is disposed axially between the ports 310 and 311 so that the plunger 304 may be slidably moved within the bore 303 for establishing alternative communication between the ports 313 and 310 and the ports 313 and 311 through said fluid passage 309. Additionally, the body 300 is provided with a fluid by-pass 318 having ports 319, 319 opening into said bore 303 at opposed ends thereof.

The manual control valve C is adapted for movement into three positions; namely, a neutral position (not shown), a gate extended position (FIG. 2), and a gate retracted position (FIG. 4); In the neutral position (not shown) the heads 306, 307 block the ports 310, 311, respectively, for prohibiting the entry of fluid from the pilot reservoir 208 to either the pilot line 207 or the conduit 212.

In the gate extended position (FIG. 2) the plunger 304 is pulled outwardly for positioning said fluid passage 309 to establish communication between ports 313 and 310 for directing fluid from the pilot reservoir 208 to the feeder port 206 of the pilot sequence valve V through the pilot line 207. Also, the port 311 is in communicationwith' the port 312 so that return flow of fluid from conduit 212 may be directed through conduit 314 to the pilot fluid reservoir 208.

In the gate retracted position (FIG. 4) the plunger 304 is pushed inwardly for locating the fluid passage 309 within bore 303 to establish communication between the ports 313 and 311 so that fluid from the pilot fluid reservoir 208 will be directed through conduits 212 and 211, as will be described. Additionally, communication is established between the ports 310 and 319 and between ports 312 and 319 for permitting return flow from the pilot line 207 through by-pass 319 and the conduit 314 to the pilot fluid reservoir 208.

OPERATION As mentioned hereinabove, a problem of the prior art elevating scrapers was that the ejector gate and the floor gate were moved simultaneously with the extent of movement being controlled by the resistance by the material accumulated in the earth collecting bowl 25. Such problem is eliminated by the present invention wherein the ejector gate 39 remains in a retracted position until the floor gate 33 has been fully extended.

Referring now to the hydraulic flow diagrams of FIGS. 2-4, the fluid control system for establishing such sequential operation of the floor gate 33 and the ejector gate 39 will be described.

FLOOR GATE EXTENSION In order to extend the floor gate 33, the vehicle operator engages the handle 305 of the manual control valve C and pulls same outwardly into its gate extended position (FIG. 2). Fluid from the pilot fluid reservoir 208 is pumped by the pump 316 through the conduits 317 and 315 into port 313 of manual control valve C, where fluid is passed through the gluid passage 309, port 310 and pilot line 207 to the feeder port 206 of the pilot sequence valve V. The spool 213 of the pilot sequence valve V is positioned within the valve chamber 204 so that feeder port 206 and the port 205 are in communication through the diametrically reduced portion 216 so that fluid is passed into the conduit 135 and the upper fluid housing 112. The fluid impinges upon the upper end portion 107 of the spool 106 for urging same downwardly into its said gate extended position (FIG. 2), thereby establishing communication between ports 121 and 122. Itwill be observed that any fluid contained in said lower fluid housing 113 will be directed to the pilot fluid reservoir 208 through conduits 231, 212 and return line 314. I

Fluid from the reservoir 126is pumped by the pump 124 through the conduits 12S and 123 into the recess 119 for direction through the conduit 54 into the port 53 of fluid responsive cylinder 38 for impingement against piston head 49 to extend the piston Y37 and the floor gate 33. Upon upward extension of the piston head 49, the fluid on the upward side thereof is forced through the port 50, branch line 51, conduit 52, upper fluid passage 114, by-pass 131,lower fluid passage and return lines 128 and 129 for return flow to the reservoir 126.

EJECTOR GATE EXTENSION When floor gate 33 has been fully extended (FIG. 3), the piston head 49 opens port 55 for permitting the fluid within the cylinder compartment 48 to enter conduit 56. Fluid is directed through the conduit 56 into the port 209 for impinging against the end wall of the forward portion 214 of spool 213. When the pressure within the valve chamber 204 is sufficient to overcome the inherent bias of the ball detents 218, the spool 213 will shift axially for closing the port 205 and opening the port 205' for establishing communication between the port 205 and the feeder port 206. Fluid from pilot line 207 is then directed through the diametrically reduced portion 216 into conduit for delivery to the upper fluid housing 1 12' of spool valve 100'. When the pressure in line 135 is relieved, upon shifting of the spool 213, through said circumferential passage 217, bore b and return line r to the pilot fluid reservoir 208,

the spool 106 of the spool valve 100 will return to its neutral position (FIG. 3). Fluid from the reservoir 126 will be directed through conduit 123, recess 119 and groove 116, passage 117, and line 118 for transmittal to the spool valve 100'. The fluid pressure in upper fluid housing 112' of spool valve 100 impinges against the upper portion 107 for urging spool 106 downwardly into its gate extended position wherein communication is'established between the ports 121' and 122 through the recess 119'. It will be observed that any fluid contained in the lower fluid housing 113' will be directed to the pilot fluid reservoir 208 through the conduits 231', 212 and the return line 314.

Fluid entering through the line 118 will be directed through the conduit 62 into the port 61 of the fluid responsive cylinder 45 for impinging against the piston head 59 thereby urging same outwardly of said fluid responsive cylinder 45. The fluid in the compartment 58 on the upward side of the piston head 59 is directed through the port 60, branch line 51, conduits 52 and 133 into the upper fluid passage 114' by-pass 131', and the lower fluid passage 115' into the return line 129 for return flow to the reservoir 126.

FLOOR GATE AND EJECTOR GATE RETRACTION When both the floor gate 33 and the ejector gate 39 are in fully extended position and it is desired to return same to their retracted position, the operator pushes inwardly on the plunger handle 305 of the manual control valve C (FIG. 4). Fluid from the pilot fluid reservoir 208 is pumped by the pump 316 through the lines 317 and 315 into the port 313 for direction through the fluid passage 309 and the port 311 for entry into the conduits 212 and 211. The fluid passing through the conduit 211 is directed to the port 210 of the pilot sequence valve V for impinging against the end wall of the rearward portion 215 for urging the spool 213 axially within valve chamber 204. The movement of spool 213 is momentarily retained by the locking engagement of the ball detents 218 within groove g. Meanwhile, fluid in conduit 212 is directed through the branch lines 231, 231 to the lower fluid housing 113, 113' wherein the fluid impinges on the lower portion 108, 108' of each spool 106, 106 for urging same into its gate retracted position (FIG. 4). As the spool 106 is moved upwardly within the bore 105 the fluid within upper fluid housing 112 is directed through the conduit 135 through the port 205, diametrically reduced portion 216 and feeder port 206 for return through the pilot line 207, port 310, and thence into port 319, by-pass 318, port 319' and port 312 for return flow through return line 314 to the pilot fluid reservoir 208. When the pressure within the valve chamber 204 is sufficient to overcome said ball detent 218 the spool 213 axially shifts thereby blocking the port 205 and establishing communication between the port 205' and the feeder port 206 so that the fluid within the upper fluid housing 112 may be returned through the conduit 135', the pilot line 207, by-pass 318 and return line 314 to the pilot fluid reservoir 208.

With both spools 106, 106' in their gate retracted position, fluid from the reservoir 126 is pumped by the pump 124 through the conduit 123, recess 119, conduit 52 for direction into the branch line 51 where fluid enters simultaneously through ports 50 and 60 into the compartments 48 and 58, respectively, of the fluid responsive cylinders 38 and 45, respectively. The fluid impinges upon the piston heads 49 and 59, respectively, for urging same into a retracted position. The fluid on the downward side of piston head 49 is directed through port 53, conduit 54 into the lower fluid passage 115, return lines 128 and 129 to the reservoir 126; and the fluid on the downward side of piston head 59, through the port 61, conduit 62 and lower fluid passage of the spool valve 101 for return through return line 129 into the reservoir 126.

Thus, by the provision of the novel pilot sequence valve V within the flow control system for the elevating scraper 20 and its discrete connection with the fluid responsive cylinder 38 of the floor gate 33, the sequential extension of floor gate 33 and ejector gate 39 is assured at all times.

Having thus described my invention, what I claim and desire to obtain Letters Patent for is:

1. In a fluid control system having a source of fluid and being adapted for sequentially moving first and second work-performing elements into extended position, a pilot sequence valve comprising:

A valve body having a chamber;

A fluid responsive member provided within said chamber for axial movement therein responsive to fluid pressure;

First conduit means for communicating the valve chamber with said source of fluid;

Second conduit means communicating said valve chamber with said first work-performing element;

Third conduit means for communicating said valve member with said second work-performing element;

Fluid pressure means for moving said fluid responsive member into first and second positions;

Wherein said first position, communication is established between said first and second conduit means for extending said first work-performing element;

And in said second position, communication is established between said first and third conduit means 'for extending said second work-performing element; v

Said fluid pressure means including fourth conduit means communicating said source of fluid with said valve chamber adjacent to one end portion of said fluid responsive member for urging same into its first position;

Said first work performing element having a port adapted for opening when said first workperforming element is in a fully extended position;

Fifth conduit means communicating said port with said valve chamber adjacent the other end portion of said fluid responsive member for urging same into its second position when said first workperforming element has been fully extended. 

1. In a fluid control system having a source of fluid and being adapted for sequentially moving first and second work-performing elements into extended position, a pilot sequence valve comprising: A valve body having a chamber; A fluid responsive member provided within said chamber for axial movement therein responsive to fluid pressure; First conduit means for communicating the valve chamber with said source of fluid; Second conduit means communicating said valve chamber with said first work-performing element; Third conduit means for communicating said valve member with said second work-performing element; Fluid pressure means for moving said fluid responsive member into first and second positions; Wherein said first position, communication is established between said first and second conduit means for extending said first work-performing element; And in said second position, communication is established between said first and third conduit means for extending said second work-performing element; Said fluid pressure means including fourth conduit means communicating said source of fluid with said valve chamber adjacent to one end portion of said fluid responsive member for urging same into its first position; Said first work performing element having a port adapted for opening when said first work-performing element is in a fully extended position; Fifth conduit means communicating said port with said valve chamber adjacent the other end portion of said fluid responsive member for urging same into its second position when said first work-performing element has been fully extended. 